System and method for managing tracking area identity lists in a mobile network environment

ABSTRACT

A method is provided in one example embodiment and includes communicating a plurality of queries associated with common tracking areas in a wireless network; identifying a set of serving gateways that serve the common tracking areas; generating a tracking area identity (TAI) list to be used in provisioning network resources for user equipment; and selecting a first serving gateway from the set of serving gateways for the user equipment, wherein the first serving gateway is selected based on the common tracking areas served by the set of serving gateways. In more specific embodiments, the queries are domain name system (DNS) queries that are supported by a network element and that have no cached DNS response.

TECHNICAL FIELD

This disclosure relates in general to the field of communications, andmore particularly, to a system and a method for managing tracking areaidentity lists in a mobile network environment.

BACKGROUND

Networking architectures have grown increasingly complex incommunications environments, particularly mobile wireless environments.Mobile data traffic has grown extensively in recent years, which hassignificantly increased the demands on radio resources. As thesubscriber base of end users increases, efficient management ofcommunication resources becomes even more critical. In some instances,failure of a network element may cause user equipment to detach and thenreattach to the network, which may waste valuable radio resources andpotentially create overload conditions in other network elements. Hence,there is a significant challenge in managing radio resources,particularly when certain network elements fail.

BRIEF DESCRIPTION OF THE DRAWINGS

To provide a more complete understanding of the present disclosure andfeatures and advantages thereof, reference is made to the followingdescription, taken in conjunction with the accompanying figures, whereinlike reference numerals represent like parts, in which:

FIG. 1 is a simplified block diagram illustrating a communication systemfor managing tracking area identity lists in a mobile networkenvironment according to one embodiment of the present disclosure;

FIG. 2 is a simplified block diagram illustrating additional detailsassociated with one potential embodiment of the communication system;

FIG. 3 is a simplified block diagram illustrating one possible set ofdetails associated with a list management database in one embodiment ofthe communication system;

FIG. 4 is a simplified flowchart illustrating example operationsassociated with processing an eNodeB setup request in one embodiment ofthe communication system;

FIG. 5 is a simplified flowchart illustrating example operationsassociated with removing an eNodeB from a database in one embodiment ofthe communication system; and

FIG. 6 is a simplified flowchart illustrating example operationsassociated with maintaining a linked list of tracking area identitiesfor serving gateway serving areas in one embodiment of the communicationsystem.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS Overview

A method is provided in one example embodiment and includescommunicating a plurality of queries associated with common trackingareas in a wireless network; identifying a set of serving gateways thatserve the common tracking areas; generating a tracking area identity(TAI) list to be used in provisioning network resources for userequipment; and selecting a first serving gateway from the set of servinggateways for the user equipment, wherein the first serving gateway isselected based on the common tracking areas served by the set of servinggateways. In more specific embodiments, the queries are domain namesystem (DNS) queries that are supported by a network element and thathave no cached DNS response.

In other instances, example embodiments of the present disclosure mayinclude relocating the user equipment to a second serving gateway in theset of serving gateways without detaching the user equipment. In othercases, the method can include relocating the user equipment to a secondserving gateway in the set of serving gateways in response to a failureof the first serving gateway. A weight factor can be calculated for eachcommon tracking area, the weight factor being representative of a numberof eNodeBs that are not in an eNodeB group of the user equipment'scurrent tracking area identity (TAI). Assigned tracking areas can bedetermined by selecting the common tracking areas having lower weightfactors.

Example Embodiments

Turning to FIG. 1, FIG. 1 is a simplified block diagram of acommunication system 10 for managing tracking area identity lists in amobile wireless network environment. This particular configuration maybe tied to the 3rd Generation Partnership Project (3GPP) Evolved PacketSystem (EPS) architecture, also sometimes referred to as the Long-TermEvolution (LTE) EPS architecture, but alternatively this depictedarchitecture may be applicable to other environments equally. Theexample architecture of FIG. 1 includes multiple end users operatinguser equipment (UE) 12 a-c and a packet data network (PDN) gateway (PGW)14, which has a logical connection to a serving gateway (SGW) 28. Alsoprovided is a home subscriber server (HSS) 18 and an Authentication,Authorization, and Accounting (AAA) element 24. SGW 28 has a logicalconnection to an eNodeB 34 and a Mobility Management Entity (MME) 40.Both SGW 28 and PGW 14 can interface with a Policy and Charging RulesFunction (PCRF) 36.

Each of the elements of FIG. 1 may couple to one another through simpleinterfaces (as illustrated) or through any other suitable connection(wired or wireless), which provides a viable pathway for networkcommunications. Additionally, any one or more of these elements may becombined or removed from the architecture based on particularconfiguration needs. Communication system 10 may include a configurationcapable of transmission control protocol/Internet protocol (TCP/IP)communications for the transmission or reception of packets in anetwork. Communication system 10 may also operate in conjunction with auser datagram protocol/IP (UDP/IP) or any other suitable protocol whereappropriate and based on particular needs.

Also provided in the architecture of FIG. 1 is a series of interfaces,which can offer mobility, policy control, AAA functions, and chargingactivities for various network elements. For example, interfaces can beused to exchange point of attachment, location, and access data for oneor more end users. Resource, accounting, location, access networkinformation, network address translation (NAT) control, etc. can beexchanged using a remote authentication dial in user service (RADIUS)protocol, or any other suitable protocol where appropriate. Otherprotocols to be used in such communications can include Diameter,service gateway interface (SGI), terminal access controlleraccess-control system (TACACS), TACACS+, etc.

There are two access cases represented in FIG. 1, which depicts these astrusted and untrusted non-3GPP IP access. For the trusted scenario, aviable relationship exists between the service provider and the corenetwork. For the untrusted scenario, a suitable security mechanism canbe provided to ensure the integrity of the data communications (e.g.,encryption and decryption operations can occur in this scenario and,further, involve an evolved packet data gateway (ePDG), which has alogical connection to PCRF 36 as shown in FIG. 1).

In more general terms, 3GPP defines the Evolved Packet System (EPS) asspecified in TS 23.401, TS.23.402, TS 23.203, etc. The EPS generallyconsists of IP access networks and an Evolved Packet Core (EPC). Accessnetworks may be 3GPP access networks, such a GERAN, UTRAN, and E-UTRAN,or they may be non-3GPP IP access networks such as digital subscriberline (DSL), Cable, WiMAX, code division multiple access (CDMA) 2000,WiFi, or the Internet. Non-3GPP IP access networks can be divided intotrusted and untrusted segments. Trusted IP access networks supportmobility, policy, and AAA interfaces to the EPC, whereas untrustednetworks do not. Instead, access from untrusted networks is done via theePDG, which provides for IPsec security associations to the userequipment over the untrusted IP access network. The ePDG (in turn)supports mobility, policy, and AAA interfaces to the EPC, similar to thetrusted IP access networks.

Before detailing the operations and the infrastructure of FIG. 1,certain contextual information is provided to offer an overview of someproblems that may be encountered while managing radio resources in amobile wireless network environment. Such information is offeredearnestly and for teaching purposes only and, therefore, should not beconstrued in any way to limit the broad applications for the presentdisclosure.

When the UE attaches to an access network, it should be assigned a listof tracking area identities (TAIs). The UE can be mobile within theseTAIs without updating the MME. If the UE moves to a TAI that is notwithin the assigned TAI list, the UE sends a Tracking Area Update (TAU)message to the MME, which triggers an SGW relocation. The data path fromthe UE to the network commonly is through an eNodeB and an SGW. An SGWcan serve a set of TAIs. Selection of a TAI list for a UE is an MMEfunction usually. The MME can ensure that all the TAIs in the TAI listare served by the selected SGW, as specified in TS 23.401. Domain NameService (DNS) procedures provide a mechanism for finding an SGW thatserves a particular TAI, but there is no such mechanism for reversemapping. Thus, there is currently no viable strategy for computing alist of TAIs that an SGW supports. Consequently, if an SGW fails whilesupporting a call, the MME detaches the UE.

Choosing another SGW that supports the current UE TAI is not sufficientsince the UE could move to a TAI that is not supported by the new SGWwithout sending a TAU to the MME (e.g., if the UE moves to a new TAIthat is in its current TAI list). Hence, a TAI-to-SGW mapping may beavailable using DNS, but the list of TAIs that an SGW supports is notreadily available. The MME should cache DNS responses for multiple TAIs,identify which SGW is common in response to multiple queries, andsuitably manage this list. Separately, any TAI list that the MME assignsto the UE should be served by the selected SGW.

Logistically, when an SGW fails in existing architectures, an MMEdetects this event. The MME is forced to detach the UEs that aresupported by the failed SGW. Without the cached and processed DNS queryresult, the most that an MME could do is to select an SGW that supportsthe current TAI of the UE; however, the MME has no mechanism forchanging the UE tracking area list. Having the cached and processed DNSquery result, but not having the SGW serving area grouping, the MMEcould attempt to find an SGW that supports all the TAIs currentlyassigned to the UE. This would be processing intensive and, furthermore,there is no mechanism to ensure that another SGW could be found.

In accordance with one embodiment, communication system 10 can overcomethe aforementioned shortcomings (and others) by providing TAI listmanagement based on SGW serving areas. When an eNodeB sends a setuprequest to an MME, and the MME accepts this request, the MME can sendDNS queries for all the TAIs that are supported by the new eNodeB, butthat currently have no cached DNS response. Note that some TAIs couldhave been queried in the context of processing setup requests fromanother eNodeB because multiple eNodeBs can service the same TAI. Byprocessing the DNS responses, the MME can build sets of SGWs that servecommon TAIs. In some embodiments, an SGW can belong to multiple sets,but the SGWs that belong to the same set can serve the same TAIs. A TAImay be an element in exactly one SGW set.

In operation, MME 40 can learn the serving areas of an SGW using DNSoperations. MME 40 is configured to construct sets or groups of SGWsthat serve common TAIs. Such groups of SGWs are included in an “SGWserving area.” According to one embodiment, a TAI belongs to exactly oneSGW serving area, where all TAIs belonging to an SGW serving area areserved by the SGWs that belong to it, and an SGW may be part of multipleSGW serving areas. Similarly, eNodeBs that serve the same TAIs may begrouped together. Such a group of eNodeBs is referred to herein as an“eNodeB group.”

When the SGW serving area solution is used, the MME can choose any SGWin the same SGW serving area. To relocate a UE in the ECM_IDLE state,the MME should create a session in the new SGW for each PDN to which theUE is attached. Similarly, to relocate a UE in the ECM_CONNECTED state,the MME should create a session in the new SGW for each PDN to which theUE is attached and, subsequently, move the UE to an idle state byreleasing the UE eNB context. The UE can then send a Service Request tostart using the network.

If the TAI list that is assigned to a UE is limited to TAIs within thesame SGW serving area, and the SGW serving a particular UE fails, thenthe MME can relocate the UE to one of the other SGWs in the SGW servingarea. The term ‘relocate’ is inclusive of operations associated withprovisioning, allocating, distributing, or otherwise managing thenetwork resources. To do SGW relocation if an SGW fails, all the TAIs inthe TAI list assigned to the UE should be supported by the new SGW.

Constructing SGW serving areas and allocating TAI lists based suchelements enables the MME to relocate the call to another SGW within theSGW serving area without having to check if all the TAIs are supportedby the new SGW. Thus, failure of an SGW could be handled similar to anSGW relocation, which avoids the paging of idle UEs, the detaching UEs,and the reattaching UEs. This could minimize interactions with networkelements and, further, conserve resources of the radio network. It alsoallows the UEs to remain attached to the EPS network if an SGW fails.

Note that in certain embodiments, the number of TAIs in a list may belimited to sixteen, which is the maximum amount that currently can beassigned in NAS messaging. The number of TAIs in a list is configurableand, therefore, can vary considerably from an operational perspective.In a particular example, the number of SGWs to be deployed for thelogical area covered by the TAIs in a list would be operator dependent.In one instance, at least two could be deployed for loadbalancing/geographical redundancy purposes. Additional details relatingto the operational capabilities of communication system 10 are providedbelow. Before turning to those capabilities and additional features, theinfrastructure of FIG. 1 is discussed.

Returning to FIG. 1, UE 12 a-c can be associated with clients orcustomers wishing to initiate a flow in communication system 10 via somenetwork. The terms ‘user equipment’, ‘mobile node’, ‘end user’, ‘and‘subscriber’ are inclusive of devices used to initiate a communication,such as a computer, a personal digital assistant (PDA), a laptop orelectronic notebook, a cellular telephone, an i-Phone, i-Pad, a GoogleDroid phone, an IP phone, or any other device, component, element, orobject capable of initiating voice, audio, video, media, or dataexchanges within communication system 10. UE 12 a-c may also beinclusive of a suitable interface to the human user such as amicrophone, a display, a keyboard, or other terminal equipment. UE 12a-c may also be any device that seeks to initiate a communication onbehalf of another entity or element such as a program, a database, orany other component, device, element, or object capable of initiating anexchange within communication system 10. Data, as used herein in thisdocument, refers to any type of numeric, voice, video, media, or scriptdata, or any type of source or object code, or any other suitableinformation in any appropriate format that may be communicated from onepoint to another. In certain embodiments, UE 12 a-c have a bundledsubscription for network access and application services (e.g., voice),etc. Once the access session is established, the user can register forapplication services as well, without additional authenticationrequirements. There can be two different user data repositories (AAAdatabases): one for the access user profile and one for the applicationuser profile. IP addresses can be assigned using dynamic hostconfiguration protocol (DHCP), Stateless Address Auto-configuration,default bearer activation, etc., or any suitable variation thereof.

PCRF 36 is a network element responsible for coordinating chargingand/or policy decisions for UE 12 a-c. PCRF 36 can be configured to usesubscription information as a basis for the policy and charging controldecisions. The subscription information may apply for both session-basedand non-session based services. PCRF 36 can maintain session linking tothe sessions via policy interactions with PGW 14 (and possibly SGW 28)and application functions (e.g., provided as part of the operator's IPservices). An application function (AF) can be provided within PCRF 36(or simply interact with PCRF 36) in order to offer applications thatrequire dynamic policy and/or charging control. The AF can communicatewith PCRF 36 to transfer dynamic session information. Additionally, anytype of policy and/or charging control element (e.g., PCCinfrastructure) can be provided within (or suitably interact with) PCRF36.

HSS 18 offers a subscriber database in 3GPP (e.g., GSM, LTE, etc.)environments. In one sense, HSS 18 can provide functions similar tothose offered by an AAA server in a CDMA environment. When a user movesto 3GPP access, HSS 18 can be aware of this location and this anchorpoint (i.e., PGW 14). Additionally, HSS 18 can communicate with AAAelement 24 such that when a UE moves to a CDMA environment, it still hasan effective anchor for communications (i.e., PGW 14). HSS 18 and AAAelement 24 can coordinate this state information for the UE (andsynchronize this information) to achieve mobility. No matter how a UEmoves, the access network element can be interacting with either HSS 18or AAA element 24 in order to identify which PGW should receive theappropriate signaling. The route to a UE can be consistently maintained,where routing topology ensures that data is sent to the correct IPaddress. Thus, synchronization activity on the backend of thearchitecture allows mobility to be achieved for the user when operatingin different environments. Additionally, in certain examples, PGW 14performs home agent functions, and the trusted non-3GPP IP accessnetwork can provide packet data serving node (PDSN) functions in orderto achieve these objectives.

AAA element 24 is a network element responsible for accounting,authorization, and authentication functions for UEs 12 a-c. For the AAAconsiderations, AAA element 24 may provide the mobile node IP addressand the accounting session identification (Acct-Session-ID) and othermobile node states in appropriate messaging (e.g., via anaccess-Request/access-Accept message). An accounting message can be sentfor the following events: accounting-start when the IP session isinitially created for the mobile node on the gateway;accounting-interim-update when a handover occurred between gateways; andan accounting-stop when the IP session is removed from the gatewayserving the element. For roaming scenarios, the home routed case isfully supported by the architecture.

The EPC generally comprises an MME, an SGW, a PGW, and a PCRF. The MMEis the primary control element for the EPC. Among other things, the MMEprovides tracking area list management, idle mode UE tracking, beareractivation and deactivation, SGW and PGW selection for UEs, andauthentication services. The SGW is a data plane element that can manageuser mobility and interfaces with Radio Access Networks. The SGW alsomaintains the data paths between eNodeBs and the PGW, and serves as amobility anchor when UEs move across areas served by different eNodeBs.The PGW provides connectivity for UEs to external packet data networks.The PCRF detects service flows and enforces charging policies.

Radio Access Networks (RANs) in an EPS architecture consist of eNodeBs(also known as eNBs). An eNodeB is generally connected directly to anEPC, as well as to adjacent eNodeBs. Connections with adjacent eNodeBsallow many calls to be routed more directly, often with minimal or nointeraction with an EPC. An eNodeB is also responsible for selecting anMME for UEs, managing radio resources, and making handover decisions forUEs.

In operation, UE 12 a can attach to the network for purposes ofestablishing a communication session. UE 12 a can communicate witheNodeB 34, which can further interact with MME 40 to complete some formof authentication for a particular user. MME 40 can interact with SGW28, which interacts with PGW 14 such that a session is being setupbetween these components. Tunnels could be established at this juncture,and a suitable IP address would also be issued for this particular user.This process generally involves a default EPS bearer being created forUE 12 a. As the session is established, PGW 14 can interact with PCRF 36to identify policies associated with this particular user, such as acertain QoS setting, bandwidth parameter, latency setting, priority,billing, etc.

Turning to FIG. 2, FIG. 2 is a simplified block diagram illustratingadditional details associated with one potential embodiment ofcommunication system 10. FIG. 2 includes PGW 14, SGW 28, eNodeB 34, PCRF36, and MME 40. Each of these elements includes a respective processor30 a-e and a respective memory element 32 a-e. MME 40 also includes aTAI list management module 26 and a TAI list management database 42 inthis particular example. Hence, appropriate software and/or hardware isbeing provisioned in MME 40 in order to facilitate the TAI listmanagement activities discussed herein. Alternatively, such a mechanismcan be provisioned in any of the other elements of FIGS. 1-2. Suchprovisioning may be based on particular operator constraints, particularnetworking environments, or specific protocol parameters. Note that incertain examples, TAI list management database 42 can be consolidatedwith memory elements (or vice versa), or the storage can overlap/existin any other suitable manner. Also depicted in FIG. 2 is UE 12 a-b,where these devices can attach to respective networks in order toconduct their communication sessions.

In one example implementation, PGW 14, SGW 28, eNodeB 34, and/or MME 40are network elements, which are meant to encompass network appliances,servers, routers, switches, gateways, bridges, loadbalancers, firewalls,processors, modules, or any other suitable device, component, element,or object operable to exchange information in a network environment.Moreover, the network elements may include any suitable hardware,software, components, modules, interfaces, or objects that facilitatethe operations thereof. This may be inclusive of appropriate algorithmsand communication protocols that allow for the effective exchange ofdata or information.

In regards to the internal structure associated with communicationsystem 10, each of PGW 14, SGW 28, eNodeB 34, and/or MME 40 can includememory elements (as shown in FIG. 2) for storing information to be usedin achieving the TAI list management operations, as outlined herein.Additionally, each of these devices may include a processor that canexecute software or an algorithm to perform the TAI list managementactivities discussed herein. These devices may further keep informationin any suitable memory element [(e.g., random access memory (RAM), readonly memory (ROM), an erasable programmable read only memory (EPROM),application specific integrated circuit (ASIC), etc.], software,hardware, or in any other suitable component, device, element, or objectwhere appropriate and based on particular needs. Any of the memory itemsdiscussed herein should be construed as being encompassed within thebroad term ‘memory element.’ The information being tracked or sent byPGW 14, SGW 28, eNodeB 34, and/or MME 40 could be provided in anydatabase, queue, register, control list, or storage structure, all ofwhich can be referenced at any suitable timeframe. Any such storageoptions may be included within the broad term ‘memory element’ as usedherein. Similarly, any of the potential processing elements, modules,and machines described herein should be construed as being encompassedwithin the broad term ‘processor.’ Each of the network elements and userequipment (e.g., mobile nodes) can also include suitable interfaces forreceiving, transmitting, and/or otherwise communicating data orinformation in a network environment.

In one example implementation, PGW 14, SGW 28, eNodeB 34, and/or MME 40include software (e.g., as part of TAI list management module 26, etc.)to achieve, or to foster, the TAI list management operations, asoutlined herein. In other embodiments, this feature may be providedexternally to these elements, or included in some other network deviceto achieve this intended functionality. Alternatively, these elementsinclude software (or reciprocating software) that can coordinate inorder to achieve the operations, as outlined herein. In still otherembodiments, one or all of these devices may include any suitablealgorithms, hardware, software, components, modules, interfaces, orobjects that facilitate the operations thereof.

Note that in certain example implementations, the TAI list managementfunctions outlined herein may be implemented by logic encoded in one ormore tangible media (e.g., embedded logic provided in an ASIC, in DSPinstructions, software [potentially inclusive of object code and sourcecode] to be executed by a processor, or other similar machine, etc.). Insome of these instances, memory elements [as shown in FIG. 2] can storedata used for the operations described herein. This includes the memoryelements being able to store software, logic, code, or processorinstructions that are executed to carry out the activities describedherein. A processor can execute any type of instructions associated withthe data to achieve the operations detailed herein. In one example, theprocessors [as shown in FIG. 2] could transform an element or an article(e.g., data) from one state or thing to another state or thing. Inanother example, the activities outlined herein may be implemented withfixed logic or programmable logic (e.g., software/computer instructionsexecuted by a processor) and the elements identified herein could besome type of a programmable processor, programmable digital logic (e.g.,a field programmable gate array (FPGA), a digital signal processor(DSP), an EPROM, EEPROM) or an ASIC that includes digital logic,software, code, electronic instructions, or any suitable combinationthereof.

Turning to FIG. 3, FIG. 3 is a simplified block diagram illustrating anexample configuration 92 associated with TAI list management module 40and TAI list management database 42. FIG. 3 shows the relationshipsbetween certain elements in one embodiment of TAI list managementdatabase 42. For example, TAI list management database 42 may storeinformation about serving gateway A and serving gateway B, which mayhave an M:N relationship to serving area 1 and to serving area 2.Serving area 1 and serving area 2, in turn, can be each associated withN TAIs. In the example of FIG. 3, serving area 1 is associated with TAI1 and TAI 2, while serving area 2 is associated with TAI 3. Each eNodeBcan be associated with one or more TAIs such that, in FIG. 3, eNodeB 1is associated with TAI 1 and TAI 2, and eNodeB 2 is associated with TAI3. Each eNodeB can also be associated with an eNodeB group. An eNodeBgroup is a set of eNodeBs that serve the same TAIs. Thus, an eNodeBgroup may be characterized by a set of TAIs and a set of eNodeBs, wherea TAI is in one eNodeB group. In FIG. 3, for example, eNodeB 1 servesboth TAI 1 and TAI 2, so eNodeB 1, TAI 1, and TAI 2 are associated witheNodeB group 1. eNodeB 2 serves TAI 3, where both are associated witheNodeB group 2.

Certain network events may affect the information in TAI list managementdatabase 42. For example, DNS queries may be used for identifying an SGWthat serves a TAI. The response to the DNS query can include a list ofall SGWs that serve the TAI. The first time a DNS query response isreceived, the list of SGWs can be compared with existing SGW servingareas. If any of the existing SGW serving areas have the same list ofSGWs as indicated in the DNS response, the TAI can be added to that SGWserving area. Otherwise, a new SGW serving area can be created and theTAI can be added to the new SGW serving area. The TAI list for the TAIthat started the query can subsequently be calculated. If the responseis a refresh, the current SGW serving area of the TAI may be checked todetermine if the DNS response includes the same set of SGWs. If not, theTAI should be removed from the SGW serving area. TAI lists of theremaining TAIs in the old SGW serving area may then be determined. A newSGW serving area for the TAI can be determined as if it was the firstDNS response. If the DNS response includes the same set of SGWs, then nofurther changes may be necessary.

FIG. 4 is a simplified flowchart 400 illustrating example operationsassociated with processing an eNodeB setup request in one exampleoperation of communication system 10. In one particular embodiment,these operations may be carried out by TAI list management module 26 inMME 40. At any time prior to a UE attaching to the network, an eNodeBcan establish a connection with MME 40 using a setup request andresponse messages. In general, the eNodeB is configured to send a listof supported TAIs in the setup request message. Thus, processing startswhen the list of TAIs is received. The first TAI in the list may becompared to existing eNodeB groups at 405. If a matching eNodeB group isfound, then the remaining TAIs in the list can be compared with the TAIlist of the matching eNodeB group at 410. If all of the TAIs in theeNodeB group are supported by the eNodeB sending the setup request, thenno further processing may be required. If the TAI list of the eNodeBdoes not fit into any existing eNodeB group, a new eNodeB group can becreated at 415. If all the TAIs that are supported by the eNodeB arenew, then a new eNodeB group is created to include the eNodeB and itsTAIs (indicated at 420), where no further processing is required.However, if at least one of the TAIs is already known, then for each TAIsupported by the eNodeB, the TAI should be removed from its currenteNodeB group at 425. If any other existing eNodeB group supports theexact list of eNodeBs as the removed TAI, then the TAI may be added tothat eNodeB group at 430. If no such eNodeB group is found, a new eNodeBgroup can be created at 435, and the removed TAI can be added to the newgroup at 435.

FIG. 5 is a simplified flowchart 500 illustrating example operationsassociated with removing an eNodeB from TAI list management database 42in one embodiment of communication system 10. In one particularembodiment, these operations may be carried out by TAI list managementmodule 26 in MME 40. Alternatively, such activities can be performed byany network element of communication system 10. For all of the eNodeBgroups to which the eNodeB belongs, the eNodeB may be removed from thegroups at 505. For each eNodeB group from which the eNodeB is removed, adetermination is made if the group can be merged with another group(indicated at 510). For example, two eNodeB groups may be merged if theyhave the same set of eNodeBs in them. If the eNodeB group (from whichthe eNodeB has been removed) can possibly be merged with another group,it can be merged with the other group at 515.

The example operations illustrated in FIG. 4 and FIG. 5 may also beassociated with processing an eNodeB configuration update request. Insome scenarios, a configuration update may not include a TAI list, inwhich case no additional processing may be necessary. However, if theconfiguration update request results in an additional eNodeB, therequest may be processed similar to that which is described above inFIG. 4. If the configuration update request results in the removal of aneNodeB, the request may be processed similarly to that which isdescribed in FIG. 5.

In one embodiment of communication system 10, TAI lists assigned to a UEare linked lists into which TAIs may be inserted or removed. As notedabove, all of the TAIs in such a list should be serviced by the sameSGW. Moreover, additional criteria may make a TAI list more effective.For example, if all of the TAIs assigned to a UE are in the same SGWserving area, an MME may be better able to process an SGW failure bytransferring calls to any of the other SGWs in the same SGW servingarea. In another example, the number of eNodeBs that need to be paged incertain scenarios may be reduced, provided the number of eNodeB groupsthat is used to generate a TAI list is reduced.

FIG. 6 is a simplified flowchart 600 illustrating example operationsassociated with maintaining a list of TAIs for a UE in one embodiment ofcommunication system 10. In one particular embodiment, these operationsmay be carried out by TAI list management module 26 in MME 40. In thisexample embodiment, the linked list may be maintained based onincreasing weights. For example, the weights may be the number ofeNodeBs that are not in the eNodeB group of the UE's current TAI. Thus,as is depicted in FIG. 6, a weight factor for adding a TAI to a TAI listis calculated by comparing the eNodeB groups of the TAIs at 605 and,subsequently, adding it to a candidate pool of TAIs at 610. Thisoperation is repeated for all the TAIs in the SGW serving area of thecurrent TAI. The TAIs with a weight factor of zero are selected as theinitial TAI list at 615. While the number of selected TAIs (X) is lessthan the maximum number of allowed TAIs (Xmax) and the total eNodeBcount (Y) is less than the maximum allowed eNodeB count (Ymax), the TAIthat is at the front of the list is selected at 620, and the rest of thelist is updated at 625. The weights of the other elements in the listmay change if new eNodeBs have been added.

The computation of a TAI list need not occur at each call instance. Forexample, the computation can be done when the information in TAI listmanagement database 42 changes in a way that could affect the TAI listfor a TAI. Certain events may trigger these changes, such as an eNodeBconfiguration update, or an S1 setup that changes the eNodeB group towhich a TAI belongs, a DNS query result that changes the SGW pool towhich the TAI belongs, or a configuration update that changes the SGWlist that supports the TAI. Once a TAI list is computed, it can beassigned on a per-call basis.

Note that with the examples provided above, as well as numerous otherexamples provided herein, interaction may be described in terms of two,three, or four network elements. However, this has been done forpurposes of clarity and example only. In certain cases, it may be easierto describe one or more of the functionalities of a given set of flowsby only referencing a limited number of network elements. It should beappreciated that communication system 10 (and its teachings) are readilyscalable and can accommodate a large number of components, as well asmore complicated/sophisticated arrangements and configurations.Accordingly, the examples provided should not limit the scope or inhibitthe broad teachings of communication system 10 as potentially applied toa myriad of other architectures. Additionally, although described withreference to particular scenarios, where a TAI list management module isprovided within the network elements, these modules can be providedexternally, or consolidated and/or combined in any suitable fashion. Incertain instances, a TAI list management module may be provided in asingle proprietary unit.

It is also important to note that the steps in the appended diagramsillustrate only some of the possible signaling scenarios and patternsthat may be executed by, or within, communication system 10. Some ofthese steps may be deleted or removed where appropriate, or these stepsmay be modified or changed considerably without departing from the scopeof teachings provided herein. In addition, a number of these operationshave been described as being executed concurrently with, or in parallelto, one or more additional operations. However, the timing of theseoperations may be altered considerably. The preceding operational flowshave been offered for purposes of example and discussion. Substantialflexibility is provided by communication system 10 in that any suitablearrangements, chronologies, configurations, and timing mechanisms may beprovided without departing from the teachings provided herein.

Numerous other changes, substitutions, variations, alterations, andmodifications may be ascertained to one skilled in the art and it isintended that the present disclosure encompass all such changes,substitutions, variations, alterations, and modifications as fallingwithin the scope of the appended claims. In order to assist the UnitedStates Patent and Trademark Office (USPTO) and, additionally, anyreaders of any patent issued on this application in interpreting theclaims appended hereto, Applicant wishes to note that the Applicant: (a)does not intend any of the appended claims to invoke paragraph six (6)of 35 U.S.C. section 112 as it exists on the date of the filing hereofunless the words “means for” or “step for” are specifically used in theparticular claims; and (b) does not intend, by any statement in thespecification, to limit this disclosure in any way that is not otherwisereflected in the appended claims.

1. A method, comprising: communicating a plurality of queries associated with common tracking areas in a wireless network; identifying a set of serving gateways that serve the common tracking areas; generating a tracking area identity (TAI) list to be used in provisioning network resources for user equipment; and selecting a first serving gateway from the set of serving gateways for the user equipment, wherein the first serving gateway is selected based on the common tracking areas served by the set of serving gateways.
 2. The method of claim 1, wherein the queries are domain name system (DNS) queries that are supported by a network element and that have no cached DNS response.
 3. The method of claim 1, further comprising: relocating the user equipment to a second serving gateway in the set of serving gateways without detaching the user equipment.
 4. The method of claim 1, further comprising: relocating the user equipment to a second serving gateway in the set of serving gateways in response to a failure of the first serving gateway.
 5. The method of claim 1, wherein a weight factor is calculated for each common tracking area, the weight factor being representative of a number of eNodeBs that are not in an eNodeB group of the user equipment's current tracking area identity (TAI).
 6. The method of claim 5, wherein assigned tracking areas are determined by selecting the common tracking areas having lower weight factors.
 7. The method of claim 1, further comprising: relocating the user equipment to a second serving gateway in the set of serving gateways without detaching the user equipment, wherein a number of particular tracking areas assigned to the user equipment is less than a preconfigured limit, and wherein a selected one of the particular tracking areas belongs to exactly one set of serving gateways.
 8. Logic encoded in non-transitory media that includes code for execution and when executed by a processor operable to perform operations comprising: communicating a plurality of queries associated with common tracking areas in a wireless network; identifying a set of serving gateways that serve the common tracking areas; generating a tracking area identity (TAI) list to be used in provisioning network resources for user equipment; and selecting a first serving gateway from the set of serving gateways for the user equipment, wherein the first serving gateway is selected based on the common tracking areas served by the set of serving gateways.
 9. The logic of claim 8, wherein the queries are domain name system (DNS) queries that are supported by a network element and that have no cached DNS response.
 10. The logic of claim 8, wherein the operations further comprise: relocating the user equipment to a second serving gateway in the set of serving gateways without detaching the user equipment.
 11. The logic of claim 8, wherein the operations further comprise: relocating the user equipment to a second serving gateway in the set of serving gateways in response to a failure of the first serving gateway.
 12. The logic of claim 8, wherein a weight factor is calculated for each common tracking area, the weight factor being representative of a number of eNodeBs that are not in an eNodeB group of the user equipment's current tracking area identity (TAI).
 13. The logic of claim 12, wherein assigned tracking areas are determined by selecting the common tracking areas having lower weight factors.
 14. The logic of claim 8, wherein the operations further comprise: relocating the user equipment to a second serving gateway in the set of serving gateways without detaching the user equipment, wherein a number of particular tracking areas assigned to the user equipment is less than a preconfigured limit, and wherein a selected one of the particular tracking areas belongs to exactly one set of serving gateways.
 15. An apparatus, comprising: a memory element configured to store electronic code; a processor operable to execute instructions associated with the electronic code; and a tracking area identity (TAI) module configured to interface with the processor such that the apparatus is configured for: communicating a plurality of queries associated with common tracking areas in a wireless network; identifying a set of serving gateways that serve the common tracking areas; generating a tracking area identity (TAI) list to be used in provisioning network resources for user equipment; and selecting a first serving gateway from the set of serving gateways for the user equipment, wherein the first serving gateway is selected based on the common tracking areas served by the set of serving gateways.
 16. The apparatus of claim 15, wherein the queries are domain name system (DNS) queries that are supported by a network element and that have no cached DNS response.
 17. The apparatus of claim 15, wherein the apparatus is further configured for: relocating the user equipment to a second serving gateway in the set of serving gateways without detaching the user equipment.
 18. The apparatus of claim 15, wherein the apparatus is further configured for: relocating the user equipment to a second serving gateway in the set of serving gateways in response to a failure of the first serving gateway.
 19. The apparatus of claim 15, wherein a weight factor is calculated for each common tracking area, the weight factor being representative of a number of eNodeBs that are not in an eNodeB group of the user equipment's current tracking area identity (TAI), and wherein assigned tracking areas are determined by selecting the common tracking areas having lower weight factors.
 20. The apparatus of claim 15, wherein the apparatus is further configured for: relocating the user equipment to a second serving gateway in the set of serving gateways without detaching the user equipment, wherein a number of particular tracking areas assigned to the user equipment is less than a preconfigured limit, and wherein a selected one of the particular tracking areas belongs to exactly one set of serving gateways. 